Abstract
With the minimum amount of time available to satisfy impending pollution regulations, a hurried programme of engine research and development was embarked upon to reduce emissions by the simplest and quickest means.
Early attempts with air injection methods had shown promising results, but installation problems resulted in efforts directed towards an engine tuning approach.
With lean set carburation and retarded ignition, tests showed that emission levels could be reached which were within striking distance of the proposed limits.
Analysis of the various modes of operation showed that deceleration peaks, and in the case of manual transmissions, gear change peaks, were highly contributing factors.
A simple type poppet valve incorporated in the throttle plate of the carburettor, and set to operate at a given manifold depression, considerably reduced emissions during deceleration and gear change, bringing composite values within the prescribed limits. Further development of the valve was undertaken and is described in the text.
The development of systems involved investigation into carburettor metering, mixture preparation, ignition timing, temperature compensation, throttle damping, and fuel cut-off.
Get full access to this article
View all access options for this article.